It is known to provide large-sized rolling bearings, in particular angular contact rolling bearings formed as slewing bearings with large diameters e.g. for wind turbine applications or applications in construction machinery, with an opening for inserting or removing rolling elements upon assembly or for maintenance works.
In angular contact rolling bearing including an opening and a plug for closing the opening is disclosed e.g. in the document WO 2012/126529.
In recent times, there is an increasing request for large-sized rolling bearings suitable for submarine applications e.g. tidal power plants, oil trilling applications or offshoring parks. As the inner face of the plugs constitutes a part of the raceway of the rolling bearing, the plugs are usually made from bearing steel, which corrodes when exposed to sea water. The corrosion is a problem because it makes the removal of the plug for maintenance purposes difficult and impairs the watertightness of the plug.
Manufacturing the plug from stainless steel causes further problems because the machining of the raceways, which is usually done in a configuration where the plug is fitted into the opening, becomes difficult and it would be impossible to achieve high quality surface properties for the raceways. Further, a piling up of material on the raceway at the boundary between different material types risks to take place. Finally, the price of plugs manufactured from materials which are resistant to the sea water is very high.
Further, treating the surface of the plug with nickel-based coatings could work but the coating wears out very rapidly after only a few mounting and unmounting cycles.